Minor C8.0 solar flare erupts at 05:54 UTC on October 17, 2025

A minor C8.0 solar flare erupted at 05:54 UTC on October 17, 2025.

Today’s flares include an M1.5 flare from region 4246, which began at 01:15 UTC, peaked at 01:28 UTC, and ended at 01:40 UTC.

In 24 hours to 00:30 UTC on October 17, solar activity reached moderate levels, with multiple M-class solar flares observed. Region 4246 remained the dominant source, producing several notable M-class events.

Minor to moderate (R1-R2) radio blackouts are likely through October 18, with a slight chance for an isolated R3 (Strong) event, mainly due to continued activity in regions 4246 and 4248. Probabilities are expected to decrease on October 19 as AR 4246 moves beyond the western limb.

Active sunspot regions presently observed on the Earth-facing solar disk include AR 4246 (N24W69 – Beta-Gamma-Delta), AR 4248 (N07W41 – Beta-Gamma), AR 4250 (N05W34 – Alpha), AR 4252 (S13E14 – Beta), AR 4254 (N10E46 – Alpha), AR 4255 (S08E38 – Beta), and AR 4256 (S16E66 – Beta).

Over the past 24 hours, the greater than 2 MeV electron flux reached high levels, peaking at 3 769 pfu at 20:15 UTC on October 16. Proton flux above 10 MeV remained at background levels. The electron flux is forecast to decrease to normal to moderate levels on October 17, returning to high levels on October 18 and 19. There remains a slight chance for a proton event above S1 – Minor levels through October 18.

Solar wind parameters reflected a mildly disturbed environment, with total field ranging from 2 to 5 nT and Bz near neutral. Solar wind speed declined from about 470 km/s to 400 km/s but increased slightly to 430-450 km/s near 20:00 UTC on October 16. Further enhancements are anticipated through October 18 due to glancing CME effects, with a trend toward nominal conditions by October 19.

Geomagnetic field activity was quiet over the past 24 hours. G1 – Minor geomagnetic storming is likely on October 17 due to glancing CME effects, with unsettled to active conditions and a chance for additional G1 – Minor storming extending into early October 19 as any residual CME influences persist.